Have you ever heard the word incumbent to mean entry-level professionals. I study new graduate nurses and I've never heard it used that way. Also, the dictionary doesn't support it, I don't think. The online dictionaries have definitions like "the holder of an office or post" or "one who occupies a particular position or place." A newly licensed nurse doesn't fit those definitions.
The word was used in a manuscript I read, referring to new graduate nurses. The authors used the term 13 times in the paper, so it clearly was intentional. Here is an example: "A study was conducted to analyze practices surrounding entry-level incumbents. It sounded so strange to me. There are so many other terms for new graduates in the literature, such as newly licensed nurses, novice nurses, new nurses, new graduates or entry-level nurses.
